The candidate is a Clinical Psychologist applying for a scientist development award for a clinician. Lindon J. Eaves, Ph.D., D.Sc., Distinguished Professor of Human Genetics and Professor of Psychiatry at the Medical College of Virginia (MCV), will be her primary preceptor. In addition, she will have the opportunity for individual supervision by other members of the MCV psychiatric genetic group including, Dr. Kenneth Kendler. A 5-year, 2-wave longitudinal study of adolescent drug use in a population-based sample of 800 14-18 year old African American twin pairs recruited from those in the Virginia School-aged Twin Registry (n=755 pairs) and the North Carolina Registry of Juvenile Twins (n=535 pairs) is proposed. On two occasions, at an approximate 2-year interval, a telephone interview screening for drug use, life events, demographics, and indices of ethnic identity will be conducted. Also proposed is a small pilot using a semi-structured psychiatric home interview (the CAPA) among families of the most severe (top 5%) drug using adolescents(N=16 families per year). Analysis of the combined longitudinal data set on the random sample of identical and non-identical twins, combined with pilot assessments of the high risk twins and their parents will address a number of specific aims concerning the etiology and developmental trajectory of drug use and later abuse in African American adolescents. These include: examination of a stage of adolescent transition to young adulthood which appears to be associated with increases in drug use among African Americans using a genetic epidemiological design; determination of whether substance use and later abuse among African American adolescents is in part genetically determined; determination of the role specific environmental factors (i.e., religious affiliation, ethnic identity, life stressors) play in drug use and later abuse in this sample; identification of how patterns of alcohol, tobacco, and drug use vary as -function of gender and age; use of a cross-lagged genetic analysis of 2-wave twin data to identify early genetic and environmental experiences influencing later risk of substance abuse. In addition to experience in all practical aspects of psychiatric genetic epidemiology provided by the specific research project, the candidate's 5 year proposed career development plan includes course work in statistical modelling, population genetics, cytogenetics, molecular genetics, medical genetics, and human genetics and individual tutelage in statistical genetics, clinical psychiatry , and diagnostic measurement.